Chemical conversion of leuco compounds



Patented Sept. 24, 1940 UNITED STATES PATENT OFFICE.

CHEMICAL CONVERSION OF LEUCO COIWPOUNDS Geoffrey Lord and George Reeves, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware No Drawing.

Application September 11, 1937, Se-

rial No. 163,440. In Great Britain September 16 Claims.

quinone derivations into the anthraquinone deanthraquinones are frequently manufactured by the action of ammonia or of an alkylamine or arylamine upon a leuco oxy-anthraquinone or a leuco oxy-amino-anthraquinone followed by oxidation of the resulting leuco amino or substituted amino anthraquinone. The oxidation of the leuco compound may be efiected by means of air though this process has the disadvantage that it frequently leaves a small amount of the 20 leuco compound incompletely oxidised. The

more .usual method of oxidation is to use an oxidising agent, i. e. a compound capable of giving up oxygen, e-. g. sodium perborate, sodium hypochlorite, sulphuric acid and manganese dioxide. These more powerful oxidising agents are capable of oxidising the leuco compound completely and readily, but on the other hand they are liable to damage the end product, which is a great disadvantage in the manufacture of dyestuffs of standard shade. All the above processes have this in common, that the leuco compound is converted to the dyestufi or completely oxidised body by the action of a body which is capable of giving up oxygen.

We have now discovered an entirely new process of converting leuco compounds into the corresponding oxidised bodies without having recourse to the use of an oxidising agent. According to the present invention the conversion 40 of the leuco compounds to the corresponding oxidised bodies isefiected by treating such leuco compounds with substances capable of chemically combining with hydrogen. In this Way the hydrogen atoms are removed from the leuco compound without the formation of water which characterises all the previously known processes. In contradistinctionto the oxidising agents previously mentioned, the substances used in accordance with the present invention are capable of giving a' very smooth conversion of the leuco compound to the oxidised body without detriment to the latter.

The substances capable of combining chemically with hydrogen used in accordance with .the present invention, hereinafter characterised as (01. 8-34) I the "dehydrogenating substances, may be of the most diverse character and substances falling into widely different classes have been found to give excellent results. The following are typical classes of dehydrogenating substances which may 6 be employed:

(a) Ketones which are capable of being formulated in the enol form. I

The simplest member of this class is acetone and this has been found to be of especial value. 10 other members are, for example, the homologues of acetone, aceto-acetic esters, B-keto-acids and pyrazolones, e. g. l-phenyl-3-methyl-5-pyrazolone. Substances such as isatin and phthalimide may also be regarded as falling in this class 5 for they each contain, either in the stable or in the pseudo form, the grouping =--CONI-I- and are thus capable of being formulated in the form in which this grouping is present as so --C(OH)=N.

This latter form, which may be regarded as the enol form, is the stable form in the case of isatin and the pseudo form in the case of phthalimide, 25 and it is in this enol form that the substances apparently act as dehydrogenating substances.

(b) Alkylene oxides, e. g. ethylene oxide, propylene oxide and the higher homologues.

It is'believed' that it has not previously been 80 recognised that alkylene oxides are capable of pseudomerisation but it is clear that this is the case from a consideration of the reaction products obtained by their use in the present invention. Thus in the case of ethylene oxide the re- 85 action products contain ethyl alcohol so that it would appear that the ethylene oxide functions as if it were vinyl alcohol. Similarly, the use of propylene oxide results in the formation of both normal propyl alcohol and ispropyl alcohol so 40 that apparently the propylene oxide functions as if it were a mixture of propenyl alcohol and isopropenyl alcohol, which latter is, of course, the enol form of acetone.

Also included in this class are the alkylene imines, e. g. ethylene imine, which have been found to function in the same way. The reaction products in the case of ethylene imine contain ethylamine.

(c) Aldehydes, e. g. acetaldehyde and benzaldehyde. These substances contain the grouping =C=O and apparently add on hydrogen to form the group =CHOH. Also included in this class are the aldehydic sugars, e. g. the aldohexoses such as glucose. 7

'(d) Substances containing an ethylene linkage, e. g .cinnamic acid, limonene, pinene and ethylene itself. The examples specified include substances in which the ethylene linkage is present in an aliphatic compound, substances in which it is present in an aromatic compound, and in which it is present in an alicyclic ring. In limonene there are two ethylene linkages, one in the alicyclic ring and the other in an aliphatic side chain. Limonene and pinene occur in commercial turpentine oils and may be used in this form.

It will be noted that all the above compounds contain a double bond or are capable of being formulated as a pseudo compound containing a double bond. In the cases of aldehydes and ketones the double bond is in the carbonyl group C= which adds on hydrogen to form the group CHOH.

Although a number of classes of dehydrogenating substances have been specified above, the invention is not limited to such classes of substances but includes the use of any substance which is capable of chemically combining with hydrogen.

The invention is of most value in the conversion to the oxidised form of leuco amino anthraquinones and leuco substituted amino anthraquinones, including the oxy derivatives of these compounds. It may, however, be applied to the oxidation of leuco compounds of oxy anthraquinones themselves, including leuco quinizarin, and leuco compounds of other anthraquinone derivatives. The invention is of greatest importance in the production of the oxidised bodies in substance, but where the conditions of the conversion are appropriate the conversion of the leuco compound to the oxidised body may take place on textile fibres. For example, where the amino or amino-oxy or substituted amino or substituted amino-oxy anthraquinones are applied to textile goods in the vatted state or in the form of free leuco compounds, conversion to the oxidised body according to the invention may take place on textile fibres. Similarly, leuco compounds other than the leuco compounds of anthraquinone derivatives may be converted by means of the present invention and generally, where the conversion conditions are appropriate, leuco compounds of vat dyes generally, including leuco esters of vat dyes, may be converted into the oxidised state on textile fibres.

Where, in the conversion of leuco compounds of amino or amino-oxy anthraquinones to the oxidised conditions by treatment with ethylene oxide or other alkylene oxides, it is desired to minimise any tendency for the alkylene oxide to oxyalkylate the leuco anthraquinone compound, the actual time taken for effecting the reaction should be reduced as much as possible. Thus, for example, the leuco anthraquinone compound may be raised to the temperature and pressure at which the conversion is most rapidly efiected before introducing the alkylene oxide into the reaction vessel.

Amino, amino-oxy and substituted amino and substituted amino-oxy anthraquinones are frequently prepared by the replacement, by amino or substituted amino groups, of hydroxy, amino or substituted amino groups in anthraquinone compounds, by treatment of the anthraquinone compounds in the leuco form with ammonia or suitable amines. The conversion into the oxidised form of the leuco compounds produced by such processes, by the process of the present invention, may in many cases be carried out continuously with the production of such leuco compounds.

Thus we have found that a number of the dehydrogenating substances are capable of being present with the leuco compounds under conditions such that amidation by ammonia or organic amines can take place without conversion of the leuco compound to the corresponding oxidised body. In consequence, the amidation of leuco hydroxy, amino, hydroxy-amino, substituted amino and hydroxy-substituted amino anthraquinones may be carried out in the presence of the dehydrogenating substances without detriment to the amidation process, and subsequently, in the same liquor, the resulting amidated leuco compounds may be converted to the corresponding oxidised bodies by a simple change of the conditions obtaining during the amidation process to the conditions necessary for carrying out the dehydrogenation process. For example) a number of the dehydrogenating substances specified above do not exhibit their dehydrogenating property until temperatures are reached which are well above those at which amidation of a leuco anthraquinone derivative can be carried out. In consequence, such substances can be present during the amidation of a leuco anthraquinone derivative and after the amidation is complete the liquor may be raised to the temperature necessary for the transformation of the leuco compound to the corresponding oxidised compound. Thus, for example, leuco anthra-' quinone compounds are not converted to the corresponding oxidised compounds by pinene at temperatures below about 90 0. whereas amidation of suitable leuco anthraquinone compounds can readily be carried out at temperatures below 90 C.

Leuco anthraquinone derivatives which can be amidated and converted to the oxidised form in this way are, for example, quinizarin, 1:415 trihydroxy anthraquinone, 1:4:5z8 tetrahydroxy anthraquinone, alizarin Bordeaux, 1 hydroxy 4 amino anthraquinone, diamine anthrarufin or diamino anthrachrysazin. The amidation may be effected, for example, by means of ammonia, alkylamines, e. g. methylamine and mono ethanolamine, or arylamines, e. g. aniline and the toluidines.

If desired,'the initial leuco compound which is subjected to the amidation process may be produced in the self-same liquor by acting on the corresponding anthraquinone starting material with a suitable reducing agent, e. g. sodium hydrosulphite. I

The following examples illustrate the invention but are not to be regarded as limiting it in any way.

THE Usn 0F ETHYLENE OXIDE Example 1' An autoclave is charged with 60 parts of leucolz4-diamino-anthraquinone and 600 parts of methyl alcohol. The autoclave'is closed and its temperature raised to 150 C. When this temperature is reached 8.75 parts of ethylene oxide are forced into the autoclave under pressure. The autoclave is then allowed to cool and the product filtered and washed with methyl alcohol. The product is 1:4-diamino-anthraquinone in an excellent state of purity.

Example 3 An autoclave is charged with 60 parts of leuco- 1:4 di(methylamino) anthraquinone, 600 parts of methyl alcohol, and 13 parts of ethylene oxide. The whole is heated at 110-120 C. for 8 hours, and the product, 1:4-di(methylamino)-anthraquinone, isolated as described in Example 1 above.

Example 4 An autoclave is charged with 60 parts of leuco- 1:4-di(hydroxy-ethylamino) -anthraquinone, 420 parts of methyl alcohol, and 13 parts of ethylene oxide. The whole is heated at 110-120 C. for 8 hours, and the product, 1:4-di(hydroxy-ethylamino) -anthraquinone, isolated as before.

Example 5 Example 4 is repeated with the following mixture:

64 parts leuco-1:4-di(hydroxy-ethylamino) -5- oxyanthraquinone, 470 parts methyl alcohol, and 13 parts ethylene oxide. The product is 1:4- di(hydroxy-ethylamino) -5-oxy-anthraquinone.

Example 6 Example 4 is repeated with the following mixture:

65 parts leuco-'1:4-di(hydroxy-ethylamino) 5:8-dioxy-anthraquinone, 500 parts methyl alcohol, and 14 parts ethylene oxide. The product is 1:4-di(hydroxy ethylamino) 5:8 dioxy-anthraquinone.

Example 7 An autoclave is charged with 40 parts of leucolz4-dioxy-anthraquinone (leuco quinizarin), 500 parts of methyl alcohol, 2 parts of caustic soda 1 (to form a sodium'compound with the leuco quinizarin), and 13 parts .of ethylene oxide. The whole is heated for 8 hours at 15.0-160 C., and the product, quinizarin, worked up in the usual way.

THE USE or PROPYLENE OxmE Example 8 An autoclave is charged with 60 parts'of leucolz4-diamino anthraquinone (the product of reaction of ammonia on leuco quinizarin), 600 parts of methylalcohol, and 1'7 parts of propylene oxide. The whole is maintained at 150-160 C. for 4 hours, cooled, filtered, the solid product washed with methyl alcohol and dried. The product is 1:4-diamino-anthraquinone'. Both normal propyl alcohol and isopropyl alcohol may be isolated from the mother liquor.

Example 9 An autoclave is charged with 40 parts of leuco- 124-dioxy-anthraquinone (leuco quinizarin), 400 parts of methyl alcohol, 2 parts of caustic soda (to form the sodium compound of leuco quiniza rin) and 15 parts of propylene oxide. The whole is maintained at 150-l60 C. for 8 hours, and the product, quinizarin, worked up in the usual way.

THE UsE or-E'rHYLENE-IMINE Example 10 Example 10 is repeated with the following mixture:

50 parts leuco-1:4-diamino-anthraquinone (the produce of reaction of ammonia on leuco quinizarin), 500 parts of methyl alcohol, and 10 parts of ethylene-imine. The product is 1:4-diaminoanthraquinone.

THE USE or GLUCOSE Example 12 An autoclave is charged with 50 parts of leuco- 1:4-diamino-anthraquinone (the product of reaction of ammonia on leuco quinizarin), 500 parts I of methyl alcohol, and 50 parts of glucose. The whole is heated at 150 C. for 8 hours, and the .product, 1:4-diamino-anthraquinone, isolated inv the usual way.

Example 13 Example 12 is repeated with the following mixture:

50 parts leuco 1:4 di(methylamino) -anthraquinone, 400 parts of industrial alcohol, and 50 parts glucose. The product is 1:4-di(methylamino) -anthraquinone.

THE USE or ACETALDEHYDE Example 14 An-autoclave is charged with 20 parts of leuco- 1:4-diamino-anthraquinone, 200 parts of ethyl alcohol, 20 parts of acetaldehyde and 2.5 parts of soda ash, and the contents heated at 150 C. for 8 hours. The product is filtered ofi and washed with ethyl alcohol. It consists of 1:4-diaminoanthraquinone.

THE UsE or BENZALDEHYDE Example 15 The process of Example 14 is repeated using, instead of the acetaldehyde, 25 parts of benzaldehyde. The product is again 1:4-diamino-anthraquinone,

THE Usr. or Aoaroma I Example 16 An autoclave is charged with parts of leuco- 1:4-diamino-anthraquinone, 200 parts methyl alcohol, 20 parts of acetone and 2.5 parts of soda ash, and the contents are heated at 150 C. for 8 hours. The product is 1:4-diamino-anthraquinone.

THE Usa or METHYL ACETO-ACETATE Example 17 The process of Example 16 is repeated using, instead 9 acetone, parts of methyl aceto-acetate. Tne product is again 1:4-diamino-anthraquinone.

THE USE or PHENYL-MErnYL-PnAzomNE Example 18 An autoclave is charged with 20 parts of leuco- 1:4-diamino-anthraquinone, 200 parts methyl alcohol, 40 parts 1phenyl-3-methyl-5-pyrazolone and 2.5 parts of soda. ash and the contents are heated at 150 C. for 8 hours. The product is filtered and washed with methyl alcohol and consists of l :4-diamino-anthraquinone.

THE USE OF ISATIN Example 19 An autoclave is charged with 50 parts of leuco- 1:4-di(methylamino) -anthraquinone, 500 parts of industrial alcohol, and 50 parts of isatin. The whole is kept at 150 C. for 8 hours, and the product, l 4-di (methylamino) anthraquinone, worked up in the usual way.

THE USE or PHTHALIMIDE Example 20 An autoclave is charged with 50 parts of leuco- 1:4-di(methylamino) anthraquinone, 500 parts of industrial alcohol, and 50 parts of phthalimide, and the whole heated for 8 hours at 150 C. The product, 1 :4-di (methylamino) anth'raquinone, is worked up in the usual way.

THE USE OF CINNAMIC Acm Example 21 Example 22' An autoclave is charged with 50 parts of leuco- 1:4-di(methylamino) anthraquinone, 500 parts of industrial alcohol, and 30 parts of cinnamic acid. The contents are kept at 150 C. for 8 hours. The product, 1:4-di(methylamino)-anthraquinone, is isolated in the usual way.

THr: USE or PINENE Example 23 An autoclave is charged with 50 parts of leuco- 1:4-di(methylamino) anthraquinone, 400 parts of industrial alcohol, and 50 parts of American turpentine oil. The whole is heated at 150 C. for 8 hours, and the product l:4-di(methylamino)- anthraquinone, isolated.

THE USE or EIHYLENE Example 24 An autoclave is charged with 20 parts of leucol :4-di(methylamino) anthraquinone and 400 parts of industrial alcohol saturated with ethylene, and the contents are heated at 150 C. for 8 hours. The product, 1:4-di (methylamino) anthraquinone, is isolated.

COMBINED PROCESS OF AMIDATION AND CONVERSION FROM LEUCO T0 OXIDISED Form Example 25 An autoclave is charged with 4 parts of leuco quinizarin, 40 parts of industrial alcohol, 6 parts of 20% methylamine solution and 3 parts of American turpentine oil. The autoclave is closed and heated at -90 C. for 6 hours, after which, the amidation being complete, the temperature is raised to and maintainedat 150 C for a further 8 hours. The contents of the autoclave are then cooled, the product filtered and washed.

CONVERSION or LEUCO COMPOUND TO Oxmrsan Com- POUND on TEXTILE Frames Example 26 Cotton fabric impregnated with leuco Hydron blue is subjected to an atmosphere of ethylene oxide at C. The leuco compound is readily converted to the corresponding oxidised compound.

Having described our invention what we desire to secure by Letters Patent is:

1. Process for the conversion to the oxidized form of a leuco compound which requires to lose hydrogen for such conversion, which comprises heating the leuco compound with an oxo com- 3. Process for the conversion to the oxidized form of a leuco compound which requires to lose hydrogen for such conversion, which comprises heating the leuco compound with acetone under such conditions that hydrogenation of the acetone and dehydrogenation of the leuco compound occur.

4. Process for the conversion to the oxidized form of a leuco compound which requires to lose hydrogen for such conversion, which comprises heating the leuco compound with an organic compound containing in one tautomeric form the group CO--NH and in another tautomeric form the group C(OH) =N-- undersuch conditions that hydrogenation of the tautomeric compound and dehydrogenation of the leuco compound occur.

5. Process for the conversion to the oxidized form of aleuco compound which requires to lose hydrogen for such conversion. which comprises heating the leuco compound in a closed vessel with isatin at a temperature and pressure at which hydrogenation of the isatin and dehydrogenation of the leuco compound occur.

6. Process for the conversion to the oxidized form of a leuco compound which requires to lose hydrogen for such conversion, which comprises heating the leuco compound with an aldehyde, which is capable of being formulated in the enol form and of chemically combining with hydrogen, under such conditions that hydrogenation of the aldehyde and dehydrogenation of the leuco compound occur.

'7. Process for the conversion to the oxidized form of a leuco compound which requires to lose hydrogen for such conversion, which comprises heating'the leuco compound with acetaldehyde under such conditions that hydrogenation of the acetaldehyde and dehydrogenation of the leuco compound occur 8. Process for the conversion of a leuco 1.4- diamino-derivative of anthraquinone into the diamino-derivative of anthraquinone into the parent unreduced form, which comprises heating the leuco compound with an organic compound containing the group CH2CO, which is capable of behaving as an isomeric unsaturated compound and of chemically combining with hydrogen, under conditions such that hydrogenation of the organic compound containing the group CH2CO and dehydrogenation of the leuco compound occur.

10. Process for the conversion to the oxidized form of a leuco compound which requires to lose hydrogen for such conversion and which is carried on textile materials, which comprises heating the textile materials with an oxo compound, which is capable of behaving as an isomeric unsaturated hydroxy compound and of chemically combining with hydrogen, under such conditions that hydrogenation of the oxo compound and dehydrogenation of the leuco compound occur.

11. Process for the conversion to the oxidized form of a leuco compound which requires to lose hydrogen for such conversion and which is carried on textile materials,

acetone and dehydrogenation of the leuco compound occur.

12. Process for the conversion to the oxidized form of a leuco compound lose hydrogen for such conversion, which comprises heating the leuco compound with analiphatic oxo compound, which is capable of behaving as an isomeric unsaturated hydroin compound and of chemically combining with hydrogen, under such conditions that hydrogenation of behaving as an isomeric unsaturated of the aliphatic oxo compound and dehydrogenation of the leuco compound occur.

13. Process for the conversion to the oxidized form of a leuco compound which requires to combining with hydrogen, under such conditions that hydrogenation of the oxo compound and dehydrogenation of the leuco compound occur.

14. Process for the conversion to the oxidized form of a leuco compound which requires to lose hydrogen for such conversion, which comprises heating the leuco compound with an oxo compound, which is capable of behaving as an isomeric unsaturated hydroxy compound and of chemically combining with hydrogen, in an anhydrous inert liquid medium under such conditions that hydrogenation of the oxo compound and dehydrogenation of the leuco compound occur.

15. Process for the conversion to the oxidized form of a leuco compound which requires to lose hydrogen for such conversion, which comprises heating the leuco compound with an oxo compound, which is capable of behaving as an isomeric unsaturated hydroxy compound and of chemically combining with hydrogen, in presence of methyl alcohol under such conditions that hydrogenation of the oxo compound and dehydrogenation of the leuco compound occur.

16. Process for the conversion to the oxidized form of a leuco anthraqui'none derivative which requires to lose hydrogen for such conversion, which comprises heating the leuco compound with an oxo compound, which is capable of behaving as an isomeric unsaturated hydroxy compound and of chemically combining with hydrogen, under such conditions that hydrogenation of the oxo compound and dehydrogenation of the leuco compound occur.

' GEOFFREY LORD. GEORGE REEVES. 

